JP2002516920A - Thermal spray method for forming thick coatings and resulting product - Google Patents

Abstract

A method and an apparatus for flame spraying materials onto a substrate to produce a coating thereon is described which involves generating a flame in a flame spraying gun (12); and feeding the material to be sprayed through the flame in the conventional way. The flame preferably imparts a temperature to the material to be sprayed of 1500 DEG C or less, preferably 1200 DEG C or less. Further, the apparatus preferably includes a cooler (16, 11, 29, 30) for cooling the substrate (19) by bringing a cryogenic fluid into contact with the substrate. Preferably the substrate is cooled so that the solidified coating (40) thereon has a temperature between 25 DEG C and 150 DEG C, preferably 25 DEG C and 100 DEG C. The apparatus and method are particularly suitable for producing superconducting coatings. <IMAGE>

Description

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to the manufacture of a target for sputtering a magnetron having a coating as part of the direct formation of a metal or ceramic coating, such as a superconducting layer or a piezoelectric layer, or a precursor of such a layer. Apparatus and method for spraying to form a coating on a flat or curved substrate, for example.

[0002]

[Technical background]

From EP-A-286 135 it is known to flame spray a composite ceramic material onto a substrate such as a tape to form a superconducting layer. It has been suggested that the substrate be preheated to a temperature of 540 ° C. or higher to slowly cool the coating. It is further recommended that the coating be treated in an atmosphere containing one of the components of the superconducting ceramic. Oxyacetylene flame is used for flame spraying. A maximum thickness of 3 mm is stated.

[0003] It is also known from US 5,196,400 to plasma spray a coating on a target for use in a sputtering magnetron for sputtering a Y-Ba-CuO superconductor coating. Deposition of thin target coatings of only 0.5 mm has been reported.

[0004] The production of superconducting powders using flame spraying is reported in US 5,140,005. Oxyacetylene flame is used. It is implicitly accepted that high flame temperatures change the stoichiometry of the components and must compensate for this by increasing the more volatile components in the raw mixture. US 5,
No. 045,365 describes a method of cooling a flame sprayed substrate with oxygen acetylene flame with water. Without special precautions, water cooling is not suitable for superconductors due to the production of water vapor.

In EP-A-355 736, the production of flat targets with metal oxides with a layer thickness of up to 3 mm is described. WO 98/0833 describes the production of <20 micron thick layers of superconducting metal oxide mixtures.

[0006] "Rapidly Solidified Thick Deposit Layers of Fe-C-Mo Alloys by F"
In a paper entitled "Lame Spraying"), a quenched thick layer of up to 1.5 mm thickness of a flame sprayed Fe-C-Mo alloy is described. For example, cryogenic gas is applied directly on the coating in the application. Special precautions were taken to manufacture the dense layers.

[0007] EP-A-586 809 describes a metal spray application of a layer of relatively homogeneous material (nickel-coated silicon), which is much easier to handle than the heterogeneous oxide mixtures considered according to the invention. Is done. A layer thickness of up to 8 mm is described, but 3
〜5 mm is preferred. Various layers including a Ni-Al layer have been proposed to improve the adhesion between the deposited layer and the substrate. The Ni-Al adhesion promoter is DE-A-33.
18 828.

[0008] Plasma spraying of superconducting materials up to 250 microns thick has been disclosed in EP-A-2887.
11 is described.

It is an object of the present invention to provide an apparatus and method for thermal spraying a heterogeneous metal oxide to form a ceramic coating on a flat or curved substrate.

It is a further object of the present invention to provide an apparatus and method for thermal spraying a heterogeneous metal oxide to form a thick-walled ceramic coating on a flat or curved substrate having a sound structure. is there.

It is a further object of the present invention to provide an apparatus and method for thermal spraying to form a thick wall of superconducting ceramic material.

It is yet a further object of the present invention to provide a thermal spray apparatus and method suitable for forming a thick walled ceramic coating on a flat or curved target to be used in a sputtering magnetron.

Still another object of the present invention is to provide a method for producing a (magnetron) vacuum sputtering target having improved thermal conductivity and electric conductivity and high mechanical strength by using a thermal spraying process using a dedicated powder compound, and a method thereof. Is to provide the target itself.

[0014]

Summary of the Invention

In one aspect of the invention, the substrate is provided with a coating of a metal oxide compound having a thickness greater than 3 mm, more preferably greater than 5 mm, and most preferably greater than 8 mm. Preferably, the coating is deposited by thermal spraying, for example, by flame or plasma spraying. Preferably, the substrate is cylindrical, and more preferably, is suitable for a cylindrical target substrate for a sputtering magnetron. The oxide compound preferably contains at least a superconducting precursor or superconductor. The thermal conductivity of the deposited material is preferably between 1 and 5 Wm ^-1 K ^-1 . When deposited on a steel substrate, the thermal conductivity of the composite material is preferably in the range of 25-125 Wm ^-1 K ^-1 . These values are particularly preferred for YBa ₂ Cu ₃ O ₇ coatings. Preferably, an adhesion promoter layer is applied on the substrate before applying the metal oxide compound coating. The adhesion promoter may be, for example, a Ni—Al layer or an In alloy layer. The deposited coating is preferably impact resistant, for example, capable of withstanding the impact of a 0.036 kg steel ball from a height of 2 meters. Preferably, about 20% or up to 30% of the noble metal is included in the oxide material to improve the electrical and thermal properties of the deposited layer. The noble metal is preferably silver. Noble metals may be included in materials sprayed as oxides or salts, such as, for example, silver nitrate or silver oxide. Preferably, the electrical resistance of the deposited layer is 15 × 10 ⁻⁶ Ohm. m, more preferably less than 10 × 10 ^-6 , most preferably 5 × 10 ^-6 Ohm. m. 1 × 10 ⁻⁶ Ohm. Values below m can also be achieved. Up to 30% of a noble metal such as silver may be added to reduce the resistivity. These values are, in particular, YBa ₂ C
Preferred for u ₃ O ₇ coating.

[0015] Static sputter deposition, wherein the electrical, thermal and mechanical properties of the deposited coating according to the invention are preferably at least 5 nm per minute, more preferably 20 nm per minute, most preferably at least 40 nm per minute. The sputtered magnetron at speed should be sufficient to apply the deposited layer to a suitable substrate.

When the superconductor precursor or superconducting material is deposited, at least 10% of the coating
More preferably, 15% is in the superconducting phase. This means that after deposition, for example, 3
Subsequent limited heat treatment at 940 ° C. over time may assist.

The invention also includes a method of depositing a superconductor precursor layer by thermal spraying on a cylindrical target for a sputtering magnetron, the layer comprising at least 3 m
m and at least 10% of this layer is in the superconducting phase. The invention also includes a method of depositing a layer on a substrate by thermal spraying, the layer comprising at least 5 mm
And the coating comprises a metal oxide.

According to one aspect of the present invention, there is provided a flame spray device for depositing a metal oxide compound on a substrate and producing a coating thereon, the flame spray device comprising: It includes a burner and an inlet for supplying the material to be sprayed through the flame, which flame gives the material to be sprayed a temperature below 1500 ° C, preferably below 1200 ° C. Preferably, the temperature applied may be slightly above the melting point of the powder to be sprayed, e.g. Preferably, the thickness of the deposited coating is greater than 3 mm, more preferably greater than 5 mm, and most preferably greater than 8 mm.

In another aspect of the present invention, there is provided a flame spray device for depositing a metal oxide compound on a substrate to produce a coating thereon, the flame spray device comprising: a flame spray gun;
A cooling system for the substrate, the cooling system including an apparatus for contacting the cryogenic fluid with the substrate. Preferably, the thickness of the deposited coating is greater than 3 mm,
More preferably greater than 5 mm, most preferably greater than 8 mm. The input material for the sprayer may be a solution of a soluble compound (eg, nitrates) that thermally decomposes to a ceramic component oxide, a liquid slurry of the ceramic component or metal powder, or a dry metal or ceramic powder or such powder, for example. It may be a precursor of a ceramic component, such as nitrates.

The present invention may provide a method of flame spraying a compound of a metal oxide material on a substrate to produce a coating on the substrate, the method comprising the steps of generating a flame; Supplying the material to be sprayed through a flame, which gives the material to be sprayed a temperature below 1500 ° C., preferably below 1200 ° C. Preferably, the temperature applied is slightly higher than the melting point of the powder to be sprayed, e.g.

[0021] The invention may also include a method of flame spraying a metal oxide compound on a substrate to produce a coating on the substrate, the method comprising generating a flame for thermal spraying the material. And cooling the substrate by contacting the cryogenic fluid with the substrate.

The present invention may also provide a method of flame spraying a superconducting ceramic material or a precursor thereof on a substrate to produce a coating on the substrate, the method comprising spraying the ceramic material. Generating a flame for deposition, depositing a coating on the substrate, and cooling the substrate in depositing the coating, wherein the solidified coating on the substrate is from room temperature (〜25 ° C.) to 150 ° C., preferably Have a temperature from room temperature (（25 ° C.) to 100 ° C. Water cooling or cryogenic fluid cooling is particularly preferred.

One of the concepts linking the above method and apparatus is the control of the total thermal energy to the thermal spray / coating system. This includes spraying distance, spray head movement speed, cylindrical substrate rotation speed, powder residence time in hot columnar jets from the spray head,
This can be achieved by carefully controlling parameters that affect the energy input, such as the particle velocity leaving the spray head, the cooling method and the cooling rate of the substrate during coating deposition.

The invention also includes a method of reconditioning a target for a sputtering magnetron by flame spraying or atmospheric pressure plasma spraying and a reconditioned target made in accordance with the method. The target material or coating is preferably a ceramic coating, especially a superconducting or superconductor precursor coating.

The final coating is preferably a metal or ceramic layer, especially a superconducting or piezoelectric layer, or a precursor thereof. The invention includes a method of spray drying a liquid to form a powder suitable for flame spraying. The spray-dried powder may be sintered. The present invention also provides a method for depositing a coating on a substrate, comprising the steps of spray-drying the precursor liquid to form a powder and flame spraying the powder to form a coating on the substrate. including. This substrate may be the target for the sputtering magnetron, and the final coating may be sputtered on the final substrate in the sputtering magnetron. The ceramic powder may be sintered after the spray drying step. The flame of the flame spray gun is preferably 1500
C., preferably at a temperature of 1200.degree. Preferably, the temperature applied may be slightly above the melting point of the powder to be sprayed, e.g. In flame spraying, the target is preferably cooled by contacting the target with a cryogenic fluid. In particular,
The cooling device should maintain the solidified coating at a temperature from room temperature (~ 25 ° C) to 150 ° C, more preferably from room temperature (~ 25 ° C) to 100 ° C.

The present invention includes an apparatus for spray drying a liquid to form a powder suitable for flame spraying. The invention may also include an apparatus for depositing a coating on a substrate, the apparatus including a spray dryer for drying the precursor liquid to a powder, and forming the coating on the substrate. A flame sprayer for flame spraying the powder. This substrate may be a target for the magnetron. further,
A target may be used to provide a sputtering magnetron for sputtering the final coating on the final substrate. The flame of the flame spray gun preferably gives the powder to be sprayed a temperature slightly above the melting point of the sprayed material. Preferably, the temperature given is below 1500 ° C, preferably below 1200 ° C. For some metal oxides, a temperature of 600 to 850C may be appropriate. In a flame sprayer, a cooling system for the target is preferably provided,
The cooling system includes a device for contacting a cryogenic fluid with a target. In particular, the cooling device should maintain the solidified coating at a temperature between room temperature (（25 ° C.) and 150 ° C., more preferably between room temperature (〜25 ° C.) and 100 ° C.

The above method is used, for example, as part of forming a superconducting or piezoelectric layer directly on a substrate such as a tape, or in a sputtering magnetron for sputtering the superconducting layer on a final substrate. May be used for the production of a coating on a target. The present invention may provide an oxide sputtering target that supports very high power losses and thus allows a high sputter deposition rate of at least 50 nm per minute.

The dependent claims set forth additional specific embodiments of the invention. Next, the present invention will be described with reference to the following drawings.

[0029]

Description of an exemplary embodiment

The present invention will be described with reference to certain embodiments and certain drawings,
The present invention is not limited to this but only by the claims.
In particular, although the invention will be described primarily with reference to the deposition of superconductor precursors or superconducting coatings, the invention is not so limited, and other heterogeneous coatings such as ceramic coatings, especially It may be used advantageously with specialty properties such as piezoelectric coatings, and especially coatings containing components that can decompose at high temperatures or are more volatile than other components. More specifically, the invention will be described with reference to the manufacture of YBa ₂ Cu ₃ O ₇ superconducting powders and coatings, but the invention is not limited thereto but only by the claims. . Further, one way of practicing the invention will be described with reference to low temperature flame spraying, but the invention is not so limited. By practicing the invention in accordance with the process details and principles described below, thick layers (thickness greater than 3 mm, more preferably greater than 5 mm, and most preferably greater than 8 mm) are suitable for use as sputtering magnetron targets. Metal oxide compound coatings have been applied to substrates, including cylindrical substrates used in rotating cathode magnetrons, by flame spraying of an oxygen acetylene flame with water cooling or by atmospheric or low pressure plasma spraying. In plasma spraying, a gas such as argon or a mixture of argon and other gases may be used to shield the plasma spray. The invention will also be described primarily in connection with the input of spray dried powder to a flame spray head. The present invention is not limited to this, and a mixture of a metal oxide containing the slurry or a mixture of a precursor of a metal oxide such as a metal nitrate and another form of the input material such as a slurry and a solution thereof may be used. Including.

FIG. 1 is a schematic view of a flame spraying apparatus 10 according to a first embodiment of the present invention. The flame spray gun is indicated generally at 12. Gun 12 may be, for example, a commercially available flame spray gun such as that available from Sulzer Metco of Westbury, New York, USA, or a high velocity gas spray (oxy-fu) available from the company.
el spraying) may be a gun. The gun 12 may be provided with an air pincher. The gun 12 may be supplied with fuel gas from tube 22, oxygen from tube 23, and gun cooling air from tube 24. Additional gases include, for example, US Pat.
957 or EP-A 413 296 may be supplied to the gun 12. The material to be coated is supplied from the hopper 21 via a conduit 26 to the gun in the form of a powder or liquid, for example a dry powder, in a slurry or solution of powder and liquid. Gun 12 is mounted on a drive (not shown), which provides the necessary movement of gun 12 to coat substrate 19. If the substrate 19 is a cylindrical target, for example for a rotating cathode magnetron, it is rotated and the movement of the gun 12 may be a simple reciprocating movement parallel to the axis of the target 19. If the substrate 19 is a flat rectangular or circular plate, the movement may be effected by a suitable robot, and may be complex, for example involving a rotating cycloidal movement. The same substrate 19 may be sprayed on several guns 12 at the same time for rapid deposition.

The fuel gas for the gun 12 may select one of acetylene, propylene, hydrogen or a similar fuel, but the invention is not necessarily limited to this.
Particularly preferred in one embodiment of the invention are lower calorific values fuels such as ethylene, natural gas or city gas, butane or propane, which are preferred because they provide a lower temperature flame than acetylene, and butane. Is particularly preferred because it provides a stable and easily controllable flame and is considered safer than acetylene when powders containing copper compounds are used. Generally, it has been recognized that the temperature of the oxygen acetylene flame is 2000 ° C. or higher. In accordance with one embodiment of the present invention, the flame of the flame spray gun 12 preferably provides a temperature sufficient to merely melt the powder to be sprayed. Temperatures of 1500 ° C or less and preferably 1200 ° C or less are preferred, and temperatures of 600 to 1000 ° C will be more preferred. Such low flame temperatures minimize the decomposition of ceramic powder components in flame spraying. In addition, the effect of evaporation of the material to be flame sprayed can be limited,
% Is possible. That is, 80% or more of the solid mass originally introduced into the gun 12 adheres to the substrate 19. Such low temperatures produce mechanically stable scratch resistant flame sprayed coatings.

The gun 12 is preferably held 7-15 cm away from the substrate 19 to be coated, depending on the size of the flame. Similar coatings were obtained using flame and plasma spray of oxygen acetylene flame. In thermal spraying, attention must be paid to the energy absorbed by the sprayed particles and the transfer of this energy to the substrate. Intensive cooling of the substrate is preferred, which may be on the side of the substrate remote from and / or on the same side as the deposited layer. By varying the velocity of the particles in the flame or plasma, the residence time therein can be varied, which may limit the amount of energy absorbed by the particles.

The material of the substrate 19 preferably has a high melting temperature and a high thermal conductivity, and preferably has a good electrical conductivity when the substrate 19 is used as a target for a sputtering magnetron. Also, the thermal expansion of the substrate material is preferably similar to that of the applied ceramic coating. According to embodiments of the present invention, the use of a substrate 19 whose thermal expansion coefficient is at least twice as high or at least half as low as the coefficient of thermal expansion of the ceramic coating due to low temperature flame spraying and / or intensive cooling of the substrate 19. Becomes possible. A non-limiting list of suitable materials may include steel, iron, stainless steel, copper or copper alloys, but the low temperature flame spraying process according to the present invention alone or intense cryogenic Combined with cooling, other materials such as paper, cardboard or polymeric materials can be used. Preferably, substrate 19 should be dry without any grease prior to deposition. Preferably, the outer surface of the metal is sandblasted and then wrapped with abrasive. A buffer layer such as a Ni-Al or In alloy may be used between the substrate and the sprayed coating. These may be applied by flame or plasma spraying before the application of the metal oxide coating.

When the substrate 19 is hard, it may be mounted on an appropriate jig. For example,
The cylindrical substrate 19 is preferably mounted on a rotating device such as a lathe. The substrate 19 may be held at each end by a rotatable chuck. The temperature of the solidified flame spray coating 40 on the surface of the substrate 19 is preferably measured by the temperature sensors 13,15. Sensor head 13 is preferably a remote sensing optical head, which is not in contact with surface 40 of the flame spray coating. The temperature to be measured is the temperature of the solidified coating 40, not the temperature of the coating immediately upon impacting the substrate 19, which may have a higher temperature. Therefore, the temperature sensor 13 is preferably mounted with a slight delay from the impact position of the flame sprayed material. Further, a temperature sensor 31 may be provided inside the substrate 19 for further control of the deposition process. Controlling the deposition temperature is an important aspect of the present invention. Controlling the temperature affects the amount of thermal stress in the coating, with lower stress reducing the likelihood of crack formation in the coating.

According to one embodiment of the invention, a means is provided for intensive cooling of the substrate 19. This is preferably a cryogenic fluid supply 16 and a delivery system 11,14,
17, a cryogenic cooler including: The delivery system may be adapted to the shape of the substrate 19. For example, for a cylindrical substrate 19, the cooling device may include a conduit 17 for supplying cryogen to the control valve 11 and regularly spaced holes 29 for distributing the cryogen within the substrate 19. Provided with the conduit 30 and the coating 40 solidified by receiving the outputs of the temperature sensors 13 and 15 and controlling the operation of the control valve 11.
And a control device 14 for maintaining the surface temperature within a specific range. Particularly preferred is a temperature range from room temperature (25-30 ° C) to 150 ° C, more preferably from room temperature to 100 ° C. Such low temperatures avoid thermal stresses between the coating 40 and the substrate 19, provide good bonding and good coating temperature, hardness and scratch resistance, and thus prolong the life of such coatings. Helps ensure stability over time. Using a cryogenic fluid such as liquid nitrogen (77 ° K) is very advantageous and economical. This is because it does not require the complexity of a completely sealed rotating inlet and outlet for the substrate 19 when water or other cooling liquid is used. In addition, cryogenic fluids such as liquid nitrogen create large temperature gradients, which increase the thermal sink-effect. Other coolants, such as water, are not excluded from the present invention.

The cylindrical substrate 19 may be sealed at one end by a seal 26 and at the other end by a rotary seal 28. The seal 28 may be provided with a hermetic feedthrough 27 for the supply of cryogenic fluid. If water cooling is used, it may be very important to provide rotating seals at both ends of the cylindrical substrate to prevent water vapor from escaping into the deposition environment. According to one embodiment of the invention, the ends 26, 27 preferably allow cryogenic fluid to escape, where the cryogenic fluid forms a shielding gas around the substrate 19 in the thermal spray process. Particularly preferred cryogenic fluids are liquid nitrogen, liquid oxygen and liquid air. In some composite ceramic materials, one or more components may be reduced in the thermal spray process.
For such materials, it can help re-oxidize the reduced components,
It may be advantageous to use a shielding gas comprising oxygen, such as liquid air or liquid oxygen. On the other hand, for other composite ceramics, it may be advantageous to reduce the contact time with oxygen at high temperatures, under such conditions liquid nitrogen is preferred or a reducing gas such as hydrogen may be included. . During coating deposition, it is preferable to control the atmosphere near the substrate 19 to prevent the presence of excess water vapor and, in particular, to prevent condensation of water on the substrate 19. This may be achieved by overall conditioning the air around the substrate 19 and reducing its dew point.

Preferably, the deposition rate is selected to maintain the substrate surface temperature described above. FIG.
Assuming a cylindrical substrate as shown in FIG.
The linear velocity of the material and the velocity of the material exiting gun 12 may be controlled to achieve the temperatures specified above. For example, if a cylindrical substrate made of stainless steel having a diameter of 15 cm and a maximum length of 40 cm is used, when depositing a YBa ₂ Cu ₃ O ₇ layer, 3
Powder delivery of 5-10 g / min has been found to be suitable to produce coatings of -10 mm. The rotational speed of the substrate 19 may be in the range of 10 to 100 RPM, the surface speed is in the range of 1 to 40 m / min, and the lengthwise supply of the gun 12 is in the range of 1 to 3 m / min. , Typically 2 meters per minute. The deposition rate per reciprocating pass of the gun 12 may be from 10 to 50 microns of coating thickness. About 10% to 15% of the deposited coating retained the lattice structure of the powder and exhibited superconducting properties. Those skilled in the art will recognize that increasing the deposition rate, increasing the deposition thickness per pass, or increasing the temperature of the flame or reducing the thermal conductivity of the substrate material will increase the thermal load on the cooling system and improve coating quality. To obtain one of these parameters
It will be appreciated that one or more may need to be adjusted. The thermal conductivity of the deposited material is preferably between 1 and 5 Wm ^-1 K ^-1 . When deposited on a steel substrate, the thermal conductivity is preferably in the range of 25-125 Wm ^-1 K ^-1 . These values are especially YB
Preferred for a ₂ Cu ₃ O ₇ coating. Preferably, an adhesion promoter layer is applied on the substrate before applying the metal oxide compound coating. The adhesion promoter is, for example, Ni
It may be an Al layer or an In alloy layer. The deposited coating is preferably impact resistant, for example, capable of withstanding the impact of a 0.036 kg steel ball from a height of 2 meters. Preferably, about 20% or up to 30% of the noble metal is included in the oxide material to improve the electrical and thermal properties of the deposited layer. The noble metal is preferably silver. Noble metals may be included in materials sprayed as oxides or salts, such as, for example, silver nitrate or silver oxide. Preferably, the electrical resistance of the deposited layer is 15 × 10 ⁻⁶ Ohm. m, more preferably less than 10 × 10 ^-6 , most preferably 5 × 10 ^-6 Ohm. m. 1 × 10 ⁻⁶ Ohm. Values below m can also be achieved. Up to 30% of a noble metal such as silver may be added to reduce the resistivity. These values are particularly preferred for YBa ₂ Cu ₃ O ₇ coatings.

FIG. 2 is a schematic diagram of a further embodiment of the flame spraying process and apparatus according to the present invention. The components of FIG. 2 having the same reference numbers as FIG. 1 represent equivalent components. Substrate 19 according to this embodiment is a foil or sheet of metal, plastic or other flexible material that is wound from unwind spool 32 to take-up spool 36. If the final coating 40 cannot be wound on a spool, the foil with the coating 40 may be drawn linearly from the unwind spool 32 and cut to a length. The coating 40, which may be a superconducting layer, is flame sprayed with a flame spray gun 12 similar to that described in connection with FIG. In particular, it is preferable to use a fuel having a lower calorific value than acetylene, such as natural gas or city gas, butane or propane. Preferably, the temperature of the flame of the gun 12 provides a temperature of 1500 ° C or less, more preferably 1200 ° C or less, to the material sprayed through the flame. This material may be in the form of a powder of the finished component of the coating 40, for example, an oxide or a precursor thereof, for example, nitrates, or a slurry of a powder, for example, an oxide, or a nitrate, for example. It may be in the form of a solution. The gun 12 may be controlled by hand or, more preferably, by a robot to effect a zig-zag movement across the width of the foil 19, thereby applying a uniform coating 40. Preferably, a layer of 10 to 50 microns thickness is applied in each pass.

The temperature of the coating 40 may be monitored by one or more optical sensors 13, 15. Foil 1
The temperature of 9 is regulated by cryogenic fluid supplied to a series of holes or jets 29 from vessel 16 via conduit 17, controllable valve 11 and conduit 30.
The valve 11 is controlled by a controller 14 to reduce the temperature of the foil as determined by the sensors 13, 15 to less than 400 ° C., preferably
Maintain between 0 and 100 ° C. Such low temperatures allow for a wide range of materials for the substrate 19, including polymeric materials, cellulosic materials, and metals. Although only one controller 14 is shown, in the present invention the foil 19 or coating 40
Are included, each having its own controllable cryogenic cooling device 11, 29, 30 for individually controlling the temperature of different parts of the system. Optionally, an optical encoder 34 may be attached to the roller 35. The optical encoder may be read by the optical sensors 37, 38 and the sensors 37, 3
The pulse frequency generated at 8 is proportional to the linear velocity of the foil 19. This value is
It may be used by controller 14 to control the complete process and maintain the temperature and coating thickness described above.

When producing the superconducting coating 40, it is preferred that no condensation of water on the coating 40 or the foil 19 occurs, so that the atmosphere around the deposition device is air-conditioned and the dew point is reduced below ambient temperature. Preferably. Preferably, the coated substrate according to the invention is stored for an extended period in a plastic bag filled with a dry inert gas such as dry nitrogen. One aspect of the invention is flame spraying of powders that already have superconducting properties in powder form. Using the method according to the present invention, it is possible to flame spray such coatings and retain 10% to 15% of the superconducting properties of the resulting coating 40 without extensive post heat treatment.

The superconducting and / or ceramic and / or metal powders used for flame spraying are preferably homogeneous and have suitable rheological properties and correct stoichiometry to produce the required properties in the final coating. Indicates a value. Typical preferred densities for superconducting powders will be within the range of 4~5gcm ^3. A non-limiting list of suitable materials that can be flame sprayed as a powder, slurry or liquid solution according to the present invention is as follows. That is, R ₁ Ba ₂ Cu ₃ O _y (where R is Y
, La, Nd, Sm, Eu , Gd, Dy, Ho, Er, Tm, Yb, Lu) or a superconducting material such as, or _{Bi 2-x Pb, x Sr} 2 Ca n-1 Cu n O y, _{Tl 2 Ba 2 Ca n-1} Cu n O 2n + 3,

[0042]

(Equation 1)

Or Ba ₂ Can _-1 O _{2n + 2} or

[0044]

(Equation 2)

Or a cuprate of general formula A _m E ₂ R _n-1 C _n O _{2n + m + 2}
High-temperature superconductor (where A, E, and R are, for example, A = Bi, Tl, Hg, Pb, C
u or a lanthanide element, E = Ba or Sr, and R = Ca or selected from various cations such as rare earth elements) or has, for example, the general formula M (Zr _x Ti _1-x ) O ₃ , M = Pb, Ba or Sr, or a refractory ceramic oxide, nitride, carbide or phosphate, such as, for example, Al ₂ O ₃ , MgO, Zr _x O _y Or metals and their alloys.

According to a further embodiment of the present invention, there is provided a method for producing a suitable ceramic powder. Starting from an aqueous solution containing the correct proportions of the salts of the metal, the reactive precursor powder can be obtained in kilogram batches using commercially available spray-drying equipment. The type of salt (mostly nitrates) should preferably be compatible with pyrolysis to oxides in further processes such as sintering or flame spraying. According to the present invention, the spray dried nitrate powder may be directly flame sprayed, or the powder may be first sintered and then flame sprayed.

A spray drying system 50 according to one embodiment of the present invention for delivery of a powder suitable for subsequent flame spraying is schematically illustrated in FIG. Input liquid is drawn from a suitable source 53 via a peristaltic pump 54 to a spray head 71. The pressurized air 51
A suction device such as a fan 63 at the end of the generally sealed system draws the air through the air dryer and optional preheater 52 into the spray head 71. Liquid from source 53 enters spray head 71, which is cooled by any suitable means 55 to prevent clogging due to premature liquid evaporation. This liquid is atomized by co-current two-fluid nozzle 71 by dry and pressurized air 51 and discharged into chamber 56 where it dries to a powder. The liquid from source 53 may be a solution of a suitable nitrate or a slurry of a suitable oxide to which other agents such as a binder have been added.

Air 65 is sucked in by fan 63, passes over heater 64, and is introduced into chamber 56 through annular orifice 72, which surrounds the outlet of spray head 71. Air 65 also heats spray head 71. The surrounding airflow 65 guides the evaporating liquid in the chamber 56 and the powder
It plays a role in preventing it from adhering to the wall of No. 6. The air throughput of fan 63 is selected so that the correct sized powder is swept out of chamber 56 through optional heater section 58 to powder collector 59. Heavier particles settle in trap 57 and are removed from the lower portion of chamber 56.

The powder collector 59 may be any suitable device such as a cyclone, bag filter or electrostatic filter, but is preferably a cyclone. The cyclone is
The powder is discharged into a removable container 60 which is sealed to the lower part of the cyclone 59. Spent air is removed via trap 61 and scrubbed in scrubber 12 to remove impurities. The final clean air is exhausted to atmosphere by a fan 63 that controls the airflow through the system.

The control systems 66-70 for the process function as follows. The rotation speed of the centrifugal air pump 53, the temperature of the heating element 64, and the flow of the sprayed air are set by the controllers 67 and 70. Airflow is measured by gauge 68. The temperature of the hot air 65 and the air in the tubing leading from the chamber 56 to the optional heater 58 is monitored using a thermocouple 66 and the final powder temperature is monitored by a temperature sensor 69.

After spray drying, the powder may be sintered in a single step. For example, to produce a superconducting powder of the general formula YBa ₂ Cu ₃ O ₇ , optionally with Ag, the necessary nitrates are dissolved in water in the correct stoichiometric ratio and spray dried as shown above. . Next, the nitrates are reduced to oxides by sintering at 920-960 ° C for 40 to 60 hours. Optionally, prior to sintering at the above temperatures and times, the nitrates may be first reduced by heating in air at 780 ° C. for 10 hours. YBa ₂ Cu ₃ O ₇ produced by this procedure
The powder is superconductive. One aspect of the present invention is to produce powders having superconducting properties by spray drying and optional sintering, which are then the lowest required to effect melting of the powders and coating formation on a substrate. Flame spraying at the temperature of the flame, during which the coating is cooled in the fastest possible manner. This procedure minimizes the degree to which the crystal structure present in the superconducting powder is hindered by the flame spraying process. Of course, the melting of the powder in flame spraying will completely destroy the crystal structure if the molten state is long. By reducing the temperature of the flame and shortening the time in the molten phase by cooling the coating very rapidly according to the invention, some local crystallographic structure is preserved in the final flame sprayed coating, e.g. About 10% of the final coating will be in the superconducting phase, thus providing the coating on the substrate with an optimal starting condition for further heat treatment to develop full superconducting properties. The addition of metallic silver improves the thermal and mechanical properties in subsequent flame spraying and magnetron sputtering.

Alternatively, the powder for flame spraying may be spray dried from a slurry of the appropriate oxide in the correct stoichiometric ratio, optionally with the addition of silver in the above apparatus according to the invention. Is also good. For example, in the manufacture of ceramic materials, a mixture of oxides is produced by sieving it individually to 40 microns and then mixing in the correct proportions to provide a stoichiometric proportion in the final coating. You may. About 60% by weight of the powder of deionized water and an organic binder such as PVA (polyvinyl acetate) equal to about 2% by weight of the powder are added and mixed to form a slurry. The slurry is then spray dried as described above to yield a powder having a particle size of 30-50 microns. Generally, the spray dried oxide slurry does not need to be sintered before flame spraying. The organic binder may be removed by burning in flame spraying or in a special sintering step.

Spray drying a 10% by weight nitrate solution typically results in an average particle size of 3 microns, with at least 90% of the particles being 0.5-5 microns. To obtain the required particle size, sintering is preferably performed as described above. By lightly grinding and sieving this sintered powder, a mass content of more than 80% and 40-80
Micron particle sizes can be obtained. Changing the appropriate concentration of the solution in the aqueous medium 53 and / or adding the binder and / or spray drying the slurry rather than the solution allows for control of the particle size of the final powder between 2 and 100 microns. For example, the invention involves the addition of an organic binder such as polyvinyl acetate (PVA) to the liquid to be spray dried to control the particle size of the final powder. Such a binder may be removed by baking in a subsequent high temperature process such as sintering. 40-8
An average particle size of 0 microns is preferred for good flame spray deposition. The final powder may be lightly milled and sieved to improve particle size homogeneity.

One aspect of the invention is the incorporation of silver metal in the final superconducting ceramic coating. This is because, as described above, the addition of silver nitrate when nitrate solutions are then flame spraying is spray dried, by incorporation of about 20 to 30 weight% of ceramic material, or Ag ₂ O powder in an oxide slurry This is then achieved by spray drying and flame spraying. The addition of silver in the flame sprayed material is beneficial for inter-particle adhesion and heat distribution in the flame spray, thus producing a strong and dense coating.
Silver improves the thermal and electrical conductivity of the flame sprayed coating, which is beneficial for the sputtering process when the substrate is used as a sputtering target. The increased conductivity allows for higher electrical throughput for the magnetron compared to a target that does not contain silver.

The flame spraying process according to the present invention allows for reconditioning of a target for a sputtering magnetron. Static race-track plasma on magnetron target in sputtering
It is well known that the presence of ma) results in erosion grooves and poor target utilization.
Using the flame spray process of the present invention, such worn targets can be reconditioned by spraying a suitable target material into the erosion grooves and reinforcing the target in those areas to its original thickness. You may. By providing the intensive cryogenic cooling described above, the overall target temperature is below 400 ° C., preferably below 150 ° C., most preferably from room temperature (（25 ° C.) to 1
It may be kept between 00 ° C. Such low temperatures result in less damage to existing target materials and also provide a mechanically strong coating on old erosion grooves. Such a process is particularly economical when the target material is expensive, such as a superconducting material. The flame spray gun 12 described above may be hand-held and follows the contour of the erosion groove of the target used to reinforce the damaged material slowly, preferably at 10 to 50 microns per pass. Preferably, gun 12 is controlled by a robot, which is programmed to perform precise movements with gun 12 to fill erosion grooves in the target.

Although the present invention has been shown and described with reference to preferred embodiments, workers skilled in the art will recognize that various changes in form and detail may be made without departing from the scope and spirit of the invention as defined in the appended claims. It will be appreciated that modifications may be made.

[Brief description of the drawings]

FIG. 1 is a schematic view of a flame spraying apparatus according to one embodiment of the present invention.

FIG. 2 is a schematic view of a flame spraying apparatus according to another embodiment of the present invention.

FIG. 3 is a schematic view of a spray drying apparatus according to another embodiment of the present invention.

[Procedural Amendment] Submission of translation of Article 34 Amendment of the Patent Cooperation Treaty

[Submission date] August 21, 2000 (2000.8.21)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4K029 BC04 DC05 DC07 DC13 4K031 AA08 AB02 AB03 AB07 AB08 CB42 DA01 DA04 EA03

Claims (16)

[Claims] 1. A composite material comprising a substrate and a coating deposited on the substrate, wherein the coating is deposited by thermal spraying, wherein the thickness of the coating is at least 5 mm, more preferably greater than 8 mm, The composite, wherein the coating comprises a metal oxide. 2. The method of claim 1, wherein the coating comprises a superconductor precursor, and wherein at least one of the coatings comprises
2. The composite of claim 1, wherein 0% is in the superconducting phase. 3. The composite material according to claim 1, which is a target for a sputtering magnetron. 4. The composite of claim 3, wherein said target is cylindrical. 5. A target for a sputtering magnetron comprising a cylindrical substrate and a coating deposited on said substrate, said coating being deposited by thermal spraying, said coating having a thickness of at least 3 mm, more preferably A target that is at least 5 mm, most preferably greater than 8 mm, wherein the coating comprises a superconductor precursor and at least 10% of the coating is in a superconducting phase. 6. The coating of claim 1, wherein said coating has a thermal conductivity of 1-5 Wm ^-1 K ^-1.
6. The target or composite material according to any one of items 1 to 5. 7. The target according to claim 1, wherein the thermal conductivity of the composite material or the target through the substrate and the coating is in a range of 25 to 125 Wm ⁻¹ K ^−1. Or composite materials. 8. The coating according to claim 1, wherein said coating is 15 × 10 ^-6 Ohm. m, more preferably 10 × 10 ⁻⁶ Ohm. m, most preferably 5 × 10 ⁻⁶ Ohm. A target or composite according to any of claims 1 to 7, having an electrical resistance of less than m. 9. The coating of 0.03 from a height of 1 m, preferably 1.5 m.
9. The target or composite according to claim 1, which is capable of withstanding the impact of a 6 kg steel ball. 10. The target or composite material according to claim 1, wherein the thermal spraying is one of plasma spraying and flame spraying. 11. A method of depositing a superconductor precursor layer by thermal spraying on a cylindrical target for a sputtering magnetron, wherein said layer has a thickness of 3 mm and at least 10% of said layer is super-conductive. A method in the conductive phase. 12. The method of depositing a layer on a substrate by thermal spraying, wherein said layer has a thickness of at least 5 mm and the coating comprises a metal oxide. 13. The method of claim 11, wherein the step of spraying is one of a flame spraying step and a low pressure or atmospheric pressure plasma spraying step. 14. The method of claim 1, wherein spraying comprises spraying a material from a spray head, wherein the material is in the form of a powder, slurry or solution.
3. The method according to 3. 15. A method of reconditioning a used target for a sputtering magnetron having an erosion groove in a target material, comprising: flame spraying or atmospheric pressure plasma spraying the target material into the erosion groove. Method. 16. A reconditioned target for a sputtering magnetron, wherein an erosion groove in the target material and into the groove to restore the thickness of the target material to the thickness of unused material. A target material that is flame sprayed or atmospheric pressure plasma sprayed.